Siemens SIMATIC ET 200S Manual page 578

Special Measures for Interference-Free Operation
Example
The following figure shows an output circuit that requires additional overvoltage
protection devices.
VDC
Figure F-1
F-2
A
4
M
EMERGENCY-OFF relay contact in the output circuit
A
8
Contact in the output circuit
Inductance requires a circuit
(see the following figures)
ET 200S Distributed I/O System
EWA-4NEB 780602402-12